Supplemental Feed and Custom Label Builder for Google Merchant Center

How to build a Google Merchant Center supplemental feed with custom labels

This tool turns a product list into a Google Merchant Center supplemental feed: a small file with your product id and up to five custom labels. Google explains the attributes on its custom label page; this builder fills them from rules you choose and keeps every value inside Google's limits.

1. Add a product list. Any file with your Merchant Center product IDs works: an export of your feed, a Shopify or WooCommerce export, or a sales report. Add cost and sales columns if you want margin and best-seller labels.
2. Check the ID column. It must hold exactly the IDs in your primary data source, or the labels won't attach to anything. Pick the cost, sales and price columns too.
3. Choose a rule for each label. Price range, margin, best sellers, on sale, or a column copied as it is (season, collection, brand).
4. Set the breaks. Price bands, margin bands and the best-seller share. The bars under the results show how many products land in each value.
5. Download or copy. Download the tab-delimited file for a file data source, or copy the rows and paste them into a Google Sheet.

Custom label ideas for Google Shopping

Google's own example plan uses one label each for season, selling rate, price range, margin and release year. Our defaults follow the same idea: custom_label_0 holds the price band, custom_label_1 the margin, custom_label_2 best seller or low seller, and custom_label_3 whether the product is on sale. Change any of them; the only rule is that each label keeps one meaning across the whole catalog.

What to do next in Merchant Center and Google Ads

1. Turn on the add-on. In Merchant Center open Settings > Add-ons and add Advanced data source management; without it the Supplemental sources tab is hidden.
2. Create the supplemental source. Go to Settings > Data sources > Supplemental sources > Add supplemental product data. Choose a file or a Google Sheets template, enter the file name, then the data source label and language of your primary source.
3. Link it to the primary source and select Create data source. The label (feed label) and language must match exactly.
4. Use the labels in Google Ads. Split products by custom label in your Shopping, Performance Max or Demand Gen campaigns, for example a separate group for high-margin best sellers.
5. Refresh monthly. Best sellers and margins change. Re-run the file with fresh sales data and upload it again.

Common supplemental feed and custom label errors

Supplemental feed ID must match the primary feed

Labels only attach when the id is the same as in the primary data source. A product list from your shop may use different IDs from your feed, so export the IDs from Merchant Center when in doubt. IDs that differ only in capital letters are flagged, because Google warns they can be confused.

Too many unique values in a custom label

Copying a column like product title gives every product its own value and quickly passes 1,000. Use labels for groups, not for single products.

Custom labels not showing in Google Ads

New labels appear in Google Ads only after Merchant Center has processed the supplemental source and the products. A missing Advanced data source management add-on, a wrong feed label or language, or IDs that don't match are the usual causes.

Rows without an ID

A supplemental feed can't add products, so rows without an ID (like a gift-wrap service line in a sales report) are left out and listed.

Quotes in Google Sheets

Google Sheets data sources don't support quoted values: a value wrapped in double quotes keeps the quotes. Paste the copied rows, don't import a CSV with quotes.